"We have mutually decided to end our marriage," the statement said. "We'll always be family and continue to cherish our relationship based on the special love, integrity, and respect we have always enjoyed."

Franchitti later responded with a tweet of his own: "@ashleyjudd family forever."

Judd, 44, has been a constant presence at Franchitti's Izod IndyCar Series races throughout their marriage, with her floppy sun hats easy to spot on pit road. While Franchitti was winning four series championships, Judd was frequently shown on TV and interviewed.

"It is difficult to overstate how proud I am of my husband," Judd told USA TODAY Sports in 2008, when Franchitti briefly left IndyCar for NASCAR. "His willingness to chuck everything he knew - and at which he excelled at the highest level - for something totally new and unknown, I think he is utterly courageous. How many of us have that type of humility and adventuresome spirit?"

Franchitti, 39, knew nothing of Judd until they were set up by friends at a 1999 wedding reception. Judd knew little about racing, but eventually said she became "as comfortable in the pits as I am barefoot in my garden."

The couple was married in a December 2001 ceremony in a castle in Scotland, which is Franchitti's home country. Franchitti's brother, race car driver Marino Franchitti, was the best man; the bride's half-sister, country singer Wynonna Judd, was maid of honor.

Wynonna and their mother, Naomi, made up the popular country duo known as The Judds. Ashley has been best known for her acting career (she recently starred in the TV series Missing and was in such 1990s hits as Heat, A Time to Kill and Kiss the Girls).

She also is an avid Kentucky Wildcats basketball fan. In fact, she and Dario attended the Final Four in New Orleans last year, where she saw her alma mater win the title.

More recently, Judd has been mulling a run for U.S. Senate in her home state of Kentucky. During a visit to Washington last week, she told reporters a campaign is something she's "taking a close look" at doing.

"The people of Kentucky need a fighter," Judd said then. "And certainly going back 10 generations, I've got some fighters from those hills in my family."

Judd has frequently traveled the world for humanitarian causes, particularly in the fight against HIV and AIDS. She's made trips to some of the poorest areas of Africa, India and Central America.

Franchitti competed in last weekend's Rolex 24 at Daytona International Speedway but finished 37th overall after his team's car suffered a gear box failure. He starts his IndyCar season in March.